1. Field of the Invention
The invention relates to a combination input and output scanner, and more particularly to a full-width read/write device incorporating a reading head and a printing head to permit substantially simultaneous reading and writing of a document original and copy thereof.
2. Description of the Prior Art
Historically, copies of document originals have been produced by a xerographic process wherein the document original to be copied is placed on a transparent platen, either by hand or automatically through the use of a document handler, and the document original illuminated by a relatively high intensity light. Image rays reflected from the illuminated document original are focused by a suitable optical system into a previously charged photoconductor, the image light rays functioning to discharge the photoconductor in accordance with the image content of the original to produce a latent electrostatic image of the original on the photoconductor. The latent electrostatic image so produced is thereafter developed by a suitable developer material commonly referred to as toner, and the developed image transferred to a sheet of copy paper brought forward by a suitable feeder. The transferred image is thereafter fixed as by fusing to provide a permanent copy while the photoconductor is cleaned of residual developer preparatory to recharging.
More recently, interest has arisen in electronic imaging where in contrast to the above described xerographic system, the image of the document original is converted to electrical signals or pixels and these signals, which may be processed, transmitted over long distances, and/or stored, are used to produce copies. In such an electronic imaging system, rather than focusing the light image onto a photoreceptor for purposes of discharging a charged surface prior to xerographic development, the optical system focuses the image rays reflected from the document original onto the image reading array which serves to convert the image rays to electrical signals. These signals could be used to create an image by some means such as operating a laser beam to discharge a xerographic photoreceptor, or by operating some direct marking system such as an ink jet or thermal transfer printing system.
The prior art related to these types of systems includes, U.S. Pat. Nos. 4,496,984 to Stoffel and 4,583,126, a division of the above identified reference, disclose an input/output scanner for simultaneously reading a document and writing a copy. The document and copy sheet are fed in back to back relation to the read/write station. A monolithic full width reading array reads each line in two steps, to improve resolution. The writing array consists of rows of ink jet nozzles, of which the number and disposition is in direct correspondence to the sensors of the read bar.
U.S. Pat. No. 4,424,524 to Daniele discloses a full width read/write LED array for scanning a document in the read mode or exposing the photoreceptor in the write mode. A Selfoc optical fiber lens array is used for focusing the full width LED array on the document or photoreceptor.
U.S. Pat. No. 4,636,871 to Oi discloses a copying machine comprising separate reading and printing arrays and a scanning mechanism for moving the subject copy. A relative movement between the copying paper sheet and print element and between the document and read element is effected so that scanning is performed in the same pattern on both the reading and printing sides.
U.S. Pat. No. 4,635,130 to Oi discloses a reading/recording apparatus comprising a reading portion having a contact-type one-dimensional image sensor, a recording portion having a contact-type one-dimensional recording head, and a selector switch portion for controlling the image sensor and recording head operation in a sequential fashion.
U.S. Pat. No. 4,7244,490 to Tanioka teaches an image input device having an original exposing portion, and image sensor portion, and a thermal head portion formed by heat generating members. The heat generating members are driven by signals originating in the image sensor portion and are used to effect printing using a thermosensitive copy medium.
A difficulty with these prior art systems is the complexity and cost of separate components, for example, the complex optics, photoreceptor and developer in a typical xerographic process such as the Daniele system. In other systems such as the Stoffel system, it is necessary for an operator to manually combine a document and copy sheet into a single unit for insertion into the machine feed rolls. Moreover, some of these systems would introduce motion quality defects into the output document, due to the relative motion between the read and write assemblies or as a result of sequential page-wide cycling of the one-dimensional read/write arrays. Furthermore, a difficulty of the prior art system, as disclosed by Tanioka, is the practical limitation of the size of such a device, as well as the requirement for a thermosensitive copy medium.
Moreover, it would be generally advantageous if the normally separate document reading and copy printing operations could be combined, thereby simplifying system operation and synchronization problems. In addition, overall system cost would be reduced through the use of fewer parts.
It is an object of the present invention, therefore, to provide a new and improved read/write scanner/printer system in which a read array and print array are both located on the same substrate to simultaneously read a document and print a copy on a copy sheet. It is another object of the present invention to provide a document that is read and a copy that is printed in a page-wide fashion across the document and copy, that is, the reading and copying operations are effected by linear arrays extending the entire width of the document and/or copy sheet at a relatively higher resolution. It is another object of the present invention to integrally affix a means for illuminating an original document and a means for focussing the light rays, as reflected from the document, to the read array on a common substrate, thereby enabling a compact, self-contained unit requiring no post manufacturing adjustments. It is a further objective of the present invention to provide a scanner/printer system with full-width read and print arrays capable of producing copies at an increased rate.